The international price of cobalt, a material used in rechargeable lithium ion batteries, rose to an eight-year high of around $27.50 per pound in mid-April, a 90% increase since the beginning of the year and 2.5 times greater than a year ago. Cobalt is "being bought on the anticipation of increasing demand for use in electric vehicles," according to an official at a major trading house.

The contract price of lithium, another material used in electric vehicle batteries, has risen about threefold compared to two years ago in China, whose market is an international benchmark for the metal.

The rise comes as automakers energize their electric vehicle strategies. A battery factory Tesla operates jointly with Panasonic in Nevada went online in January. Costing around $5 billion, it is one of the world's largest battery factories and will supply batteries for Tesla's Model 3 car, which is to begin production this year. It is believed the Model 3 has already received about 400,000 orders.

Nissan, meanwhile, will release a new model of its leading electric car, the Leaf, in the near future, Chairman Carlos Ghosn said in January at the CES electronics show in Las Vegas, Nevada.

In addition to growing demand for use in electric cars, rare metals have surged due to supply chain concerns. Cobalt is a byproduct of nickel and copper, but supply is falling as mining companies roll back production due to a sluggish copper market and stronger environmental regulations. Some are also worried about instability in the Democratic Republic of the Congo, which is a major producer of cobalt.

Reducing battery costs has become a task for electric car developers. Nissan is holding negotiations to sell a battery joint venture with NEC, hoping to lower costs by procuring batteries from outside manufacturers.

Cobalt is said to account for about 20% of the components cost for batteries. Domestic battery manufacturers are worried that a further rise in price could make it difficult to procure materials and lead to delays in development.